Reduction of thermal magnetic field noise in TEM corrector systems

ABSTRACT

Systems for reducing the generation of thermal magnetic field noise in optical elements of microscope systems, are disclosed. Example microscopy optical elements having reduced Johnson noise generation according to the present disclosure comprises an inner core composed of an electrically isolating material, and an outer coating composed of an electrically conductive material. The product of the thickness of the outer coating and the electrical conductivity is less than 0.01Ω −1 . The outer coating causes a reduction in Johnson noise generated by the optical element of greater than 2×, 3×, or an order of magnitude or greater. In a specific example embodiment, the optical element is a corrector system having reduced Johnson noise generation. Such a corrector system comprises an outer magnetic multipole, and an inner electrostatic multipole. The inner electrostatic multipole comprises an inner core composed of an electrically isolating material and an outer coating composed of an electrically conductive material.

BACKGROUND OF THE INVENTION

Thermal magnetic field noise (Johnson noise) from magnetic andnon-magnetic conductive parts close to the electron beam recently hasbeen identified as a reason for decoherence in electron microscopysystems. Thermal magnetic field noise originates from thermally drivencurrents in the conductive magnetic as well as non-magnetic materialsclose to the imaging beam, such as yokes, lenses, and multipoles. Thisis especially an issue in chromatic aberration correctors (C_(C))(corrector systems designed to correct for the axial chromaticaberration coefficient) and C_(C)/C_(S) correctors (which correct forC_(C) and for the spherical aberration coefficient) which remove primaryresolution limiting factors, causing thermal magnetic field noise to bea limiting aberration in high-resolution TEM systems. For example, in aquadrupole-octupole C_(C)/C_(S) corrector, the main contribution tothermal magnetic field noise comes from the two C_(C) correctingelements (i.e., quadrupole Wien filters). Thus, while current TEMC_(C)/C_(S) correctors are able to compensate for spherical andchromatic aberrations, they also generate thermal magnetic field noisethat at least partially causes a severe dampening of spatial frequencieslarger than ˜1 Å⁻¹. This problem worsens for large gap objective lensesfor which the blur caused by thermal magnetic field noise increases withthe square root of the lens gap.

As thermal magnetic field noise scales with the square root oftemperature, cooling solutions have been suggested to compensate forthis thermal magnetic field noise. For example, to address thermalmagnetic field noise cooling systems using various techniques/elementssuch as liquid nitrogen, heat pipes, and/or cooling rods have beendevised. However, the cooling of a C_(C)/C_(S) corrector is bothchallenging to design and expensive to implement, making it not apractical solution outside of cryogenic systems. Accordingly, a lessexpensive and easier to implement solution to correct for thermalmagnetic field noise in imaging systems is desired.

SUMMARY

Systems for reducing the generation of thermal magnetic field noise inoptical elements of microscope systems, are disclosed. An examplemicroscopy optical element having reduced Johnson noise generationaccording to the present disclosure comprises an inner core composed ofan electrically isolating material, and an outer coating composed of anelectrically conductive material. The product of the thickness of theouter coating (t) and the electrical conductivity (σ) is less than0.01Ω⁻¹, 0.001 Ω⁻¹, 0.0001 Ω⁻¹. The outer coating according to thepresent invention causes a reduction of 2×, 3×, an order of magnitude,or greater in the Johnson noise generated by the optical element. In aspecific example embodiment, the optical element is a corrector systemhaving reduced Johnson noise generation. Such a corrector systemcomprises C_(C) correcting elements which consist of an outer magneticmultipole, and an inner electrostatic multipole. The inner electrostaticmultipole comprises an inner core composed of an electrically isolatingmaterial and an outer coating composed of an electrically conductivematerial.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentify the figure in which the reference number first appears. Thesame reference numbers in different figures indicates similar oridentical items.

FIG. 1 schematically illustrates an optical component configured toreduce thermal magnetic noise in microscope imaging systems, accordingto the present invention.

FIG. 2 depicts an environment of a microscope imaging system includingone or more optical components configured to reduce thermal magneticnoise during processing, imaging, and/or evaluation of samples.

FIGS. 3 and 4 shows a schematic diagram example corrector systemsconfigured according to the present invention to generate reducedthermal magnetic noise during use in charged particle microscope systems

FIG. 5 shows an example graph that illustrates the contribution ofThermal magnetic noise (Johnson noise) to the optical transfer functionfor various system configurations, according to the present invention

Like reference numerals refer to corresponding parts throughout theseveral views of the drawings. Generally, in the figures, elements thatare likely to be included in a given example are illustrated in solidlines, while elements that are optional to a given example areillustrated in broken lines. However, elements that are illustrated insolid lines are not essential to all examples of the present disclosure,and an element shown in solid lines may be omitted from a particularexample without departing from the scope of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Methods and systems for reducing thermal magnetic noise in microscopeimaging systems, are disclosed. Specifically, the methods and systemsinvolve an optical component that comprises an inner core composed of anelectrically isolating material and an outer coating made of anelectrically conductive material that encloses the inner core. In someembodiments of the disclosed invention, the optical component is anelectrostatic multipole of a corrector (e.g., a C_(C)/C_(S) corrector)comprising one or more inner electrostatic multipoles and one or moreouter magnetic multipoles. In some example embodiments, the presence ofthis electrically conductive material layer enclosing the innerelectrically isolating core reduces the generation of thermal magneticfield noise by the corrector by 2×, 3×, an order of magnitude, or more.

FIG. 1 is a schematic illustration of an optical component 100configured to reduce thermal magnetic noise in microscope imagingsystems, according to the present invention. Specifically, FIG. 1 showsa cross section of an optical component 102 proximate to a chargedparticle beam path 104. FIG. 1 illustrates the charged particle beampath 104 as traveling along a z-axis, and the cross section of theoptical component 102 as being bisected by an xy-plane. The opticalcomponent 102 comprises an inner core 106 composed of an electricallyisolating material. In various embodiments, the inner core 106 may becomposed of various electrically resistant materials such as a ceramicmaterial, a vitreous material, quartz, a semiconductor material, etc. Aperson having skill in the art would understand that this list ofpotential electrically resistant materials is not exhaustive, and thatvarious electrically isolating materials (and/or combinations thereof)may be selected according to the function of the optical element or thesystem in which it resides.

FIG. 1 further shows the optical element 102 as comprising an outercoating 108 composed of an electrically conductive material thatcompletely encloses the inner core. However, in other embodiments theouter coating may not completely encloses the inner core. Theelectrically conductive material is selected such that the product ofthe thickness of the outer coating (t) and the electrical conductivity(σ) of the electrically conductive material is less than 0.01Ω⁻¹, 0.001Ω⁻¹, and/or 0.0001 Ω⁻¹. In various embodiments, the outer coating 108can be electrically grounded and/or a voltage applied to the outercoating 108. Moreover, in different embodiments the outer coating 108may have a sheet resistance (i.e., 1/(σ×t)) that is greater than 10 kΩ,and/or greater than 100 kΩ. The presence of this outer coating 108 onthe optical element 102 causes the amount of thermal magnetic fieldnoise (i.e., Johnson noise) that is generated by the optical element 102to be reduced by at least 2×, 3×, or an order of magnitude over knownoptical elements.

In various embodiments of the present invention, the optical element 102may correspond to various optical microscope elements, or componentelements thereof. For example, the optical element 102 may correspond toan electrode, a multipole element, a deflector, or a component elementof a corrector, such as a C_(C) and/or C_(S) corrector.

FIG. 1 also illustrates the optical component 100 as including anoptional second optical element 110 comprising an inner core 106composed of an electrically isolating material that is enclosed by anouter coating 112 composed of an electrically conductive material. Anexample embodiment having two such optical elements may be a beamdeflector system. According to the present invention, such a beamdeflector system would be able to cause deflections of the chargedparticle beam 104 while generating a greatly reduced amount of thermalmagnetic noise when the charged particle beam 104 passes proximate tothe optical elements 102 and 110.

FIG. 2 is an illustration of an environment 200 of a microscope imagingsystem including one or more optical components configured to reducethermal magnetic noise during processing, imaging, and/or evaluation ofsamples. Specifically, FIG. 2 shows an example environment 200 thatincludes an example microscope system(s) 202 for investigating of asample 204 that includes both a deflector system 206 and a correctorsystem 208 that are each configured according to the present inventionto reduce the amount of thermal magnetic field noise they generate.Specifically, FIG. 2 shows the example microscope system(s) 202 asincluding a C_(S)/C_(C) corrector system 208.

The example microscope system(s) 202 may be or include one or moredifferent types of optical, and/or charged particle microscopes, suchas, but not limited to, a scanning electron microscope (SEM), a scanningtransmission electron microscope (STEM), a transmission electronmicroscope (TEM), a charged particle microscope (CPM), a cryo-compatiblemicroscope, focused ion beam (FIB) microscope, dual beam microscopysystem, or combinations thereof. FIG. 2 shows the example microscopesystem(s) 202 as being a TEM microscope system.

FIG. 2 depicts the example microscope system(s) 202 as including anelectron source 210 (e.g., a thermal electron source, Schottky-emissionsource, field emission source, etc.) that emits an electron beam 212along an electron emission axis 214 and towards the sample 204. Theelectron emission axis 214 is a central axis that runs along the lengthof the example microscope system(s) 202 from the electron source 210 andthrough the sample 204. While FIG. 2 depicts the example microscopesystem(s) 202 as including an electron source 210, in other embodimentsthe example microscope system(s) 202 may comprise a charged particlesource, such as an ion source, configured to emit a plurality of chargedparticles toward the sample 204.

An accelerator lens 216 accelerates/decelerates, focuses, and/or directsthe electron beam 216 towards an electron focusing column 218. Theelectron condenser column 218 focuses the electron beam 212 so that itis incident on at least a portion of the sample 204. Additionally, thecondenser column 218 may correct and/or tune aberrations (e.g.,geometric aberrations, chromatic aberrations) of the electron beam 212.In some embodiments, the electron focusing column 218 may include one ormore of an aperture, transfer lenses, scan coils, condenser lenses,deflectors 206, objective lens, etc. that together focus electrons fromelectron source 210 onto a small spot on the sample 204 (STEM mode), orprovide a wider illumination beam on the sample (TEM mode).

FIG. 2 further depicts an inset cross-sectional view 220 of a deflector206 according to the present invention, configured to provide anelectrical field to deflect the beam. Cross-sectional view 220 shows thedeflector 206 as comprising an inner core 222 composed of anelectrically isolating material. In various embodiments, the inner core222 may be composed of various electrically resistant materials such asa ceramic material, a vitreous material, quartz, a semiconductormaterial, etc. A person having skill in the art would understand thatthis list of potential electrically resistant materials is notexhaustive, and that various electrically isolating materials (and/orcombinations thereof) may be selected according to the function of theoptical element or the system in which it resides. Deflector 206 isfurther shown as comprising an outer coating 224 composed of anelectrically conductive material that completely encloses the innercore. The electrically conductive material is selected such that theproduct of the thickness of the outer coating (t) and the electricalconductivity (σ) of the electrically conductive material is less than0.01Ω⁻¹, 0.001 Ω⁻¹, and/or 0.0001 Ω⁻¹. In various embodiments, the outercoating 224 may be electrically grounded, and/or may have a sheetresistance that is greater than 10 kΩ, and/or greater than 100 kΩ. Thepresence of this outer coating 224 on the deflector 206 causes theamount of thermal magnetic noise (i.e., Johnson noise) that is generatedby the deflector 206 to be reduced by at least 2×, 3×, or an order ofmagnitude over known optical elements.

Different locations of the sample 204 may be scanned by adjusting theelectron beam direction via the deflectors 206 and/or scan coils. Inthis way, the electron beam 212 acts as an imaging beam that is scannedacross a surface layer of the sample (i.e., the surface of the layerproximate the microscope column 202 and/or that is irradiated by theelectron beam 212). This irradiation of the surface layer of the sample204 causes the component electrons of the electron beam 212 to interactwith component elements/molecules/features of the sample, such thatcomponent elements/molecules/features cause emissions to be emitted bythe sample 204. The specific emissions that are released are based onthe corresponding elements/molecules/features that caused them to beemitted, such that the emissions can be analyzed to determineinformation about the corresponding elements/molecules.

FIG. 2 further illustrates a detector system 226 for detecting emissionsresultant from the electron beam 212 being incident on the sample 204.The detector system 226 may comprise one or more detectors positioned orotherwise configured to detect such emissions. In various embodiments,different detectors and/or different portions of single detectors may beconfigured to detect different types of emissions, or be configured suchthat different parameters of the emissions detected by the differentdetectors and/or different portions.

FIG. 2 further includes an inset cross-sectional view 230 of a correctorsystem 208 according to the present invention. The corrector system 208comprises a plurality of outer magnetic elements 232 (e.g., a magneticmultipole comprising 8 or 12 poles) and a plurality of electrodes 234(e.g., an electrostatic multipole), where the electrodes 234 arepositioned more proximate to the charged particle beam 212 than theouter magnetic elements 232.

Cross-sectional view 230 shows the electrodes 234 as comprising an innercore composed of an electrically isolating material (e.g., a ceramicmaterial, a vitreous material, quartz, a semiconductor material, etc.)and an outer coating composed of an electrically conductive materialthat completely encloses the inner core. The electrically conductivematerial is selected such that the product of the thickness of the outercoating (t) and the electrical conductivity (σ) of the electricallyconductive material is less than 0.01Ω⁻¹, 0.001 Ω⁻¹, and/or 0.0001 Ω⁻¹.In various embodiments, the outer coating may be electrically grounded,and/or may have a sheet resistance that is greater than 10 kΩ and/orgreater than 100 kΩ. The presence of this outer coating 224 on theelectrodes 234 causes the amount of thermal magnetic noise (i.e.,Johnson noise) that is generated by the corrector system 208 to bereduced by at least 2×, 3×, or an order of magnitude over known opticalelements. FIG. 2 further shows the corrector system 208 as optionallyincluding a barrier between the magnetic elements 232 and the electrodes234. For example, the barrier 236 may partially define a vacuum regionthrough which the charged particle beam 212 travels.

FIG. 2 further illustrates the example microscope system(s) 202 asfurther including a sample holder 228. The sample holder 228 isconfigured to hold the sample 204, and can translate, rotate, and/ortilt the sample 204 in relation to the example microscope system(s) 202.

The environment 200 is also shown as including one or more computingdevice(s) 238 connected to the detector system 226. The detector system226 is further configured to generate a data/data signal correspondingto the detected emissions, and transmit the data/data signal to one ormore computing devices 238. Those skilled in the art will appreciatethat the computing devices 238 depicted in FIG. 2 are merelyillustrative and are not intended to limit the scope of the presentdisclosure. The computing system and devices may include any combinationof hardware or software that can perform the indicated functions,including computers, network devices, internet appliances, PDAs,wireless phones, controllers, oscilloscopes, amplifiers, etc. Thecomputing devices 238 may also be connected to other devices that arenot illustrated, or instead may operate as a stand-alone system.

It is also noted that one or more of the computing device(s) 238 may bea component of the example microscope system(s) 202, may be a separatedevice from the example microscope system(s) 202 which is incommunication with the example microscope system(s) 202 via a networkcommunication interface, or a combination thereof. For example, anexample microscope system(s) 202 may include a first computing device238 that is a component portion of the example microscope system(s) 202,and which acts as a controller that drives the operation of the examplecharged particle microscope system(s) 202 (e.g., adjust the scanninglocation on the sample by operating the scan coils, etc.). In such anembodiment the example microscope system(s) 202 may also include asecond computing device 238 that is desktop computer separate from theexample microscope system(s) 202, and which is executable to processdata received from the detector system 226 to generate images of thesample 204 and/or perform other types of analysis or post processing ofdetector data. The computing devices 238 may further be configured toreceive user selections via a keyboard, mouse, touchpad, touchscreen,etc.

FIGS. 3 and 4 are schematic illustrations of example corrector systemsconfigured according to the present invention to generate reducedthermal magnetic noise during use in charged particle microscopesystems. For example, FIG. 3 illustrates an example C_(C) correctingelement of a C_(S)/C_(C) corrector system 300 according to the presentinvention. Specifically, FIG. 3 shows the example C_(S)/C_(C) correctorsystem 300 as comprising a magnetic multipole 302 surrounding anelectrostatic quadrupole formed by a plurality of electrodes 304.

FIG. 3 depicts cross sectional views of the electrodes 304 thatillustrate that the electrodes 304 are individually formed of a an innercore 306 composed of an electrically isolating material (e.g., a ceramicmaterial, a vitreous material, quartz, a semiconductor material, etc.)and an outer coating 308 composed of an electrically conductive materialthat completely encloses the inner core. The electrically conductivematerial is selected such that the product of the thickness of the outercoating (t) and the electrical conductivity (σ) of the electricallyconductive material is less than 0.01Ω⁻¹, 0.001 Ω⁻¹, and/or 0.0001 Ω⁻¹.In various embodiments, the outer coating 308 may be electricallygrounded, and/or may have a sheet resistance that is greater than 10 kΩ,and/or greater than 100 kΩ. The presence of this outer coating 308 onthe electrodes 302 causes the amount of thermal magnetic noise (i.e.,Johnson noise) that is generated by the example C_(S)/C_(C) correctorsystem 300 to be reduced by at least 2×, 3×, or an order of magnitudeover known optical elements when a charged particle beam 310 travelsproximate to the electrodes 302. FIG. 3 also illustrates exampleC_(S)/C_(C) corrector system 300 as including an optional barrier 312that partially defines a vacuum region through which the chargedparticle beam 310 travels during operation of the example C_(S)/C_(C)corrector system 300. However, in other embodiments such an optionalbarrier 312 may be positioned such that the magnetic multipole isenclosed within the vacuum region.

FIG. 4 illustrates an example C_(C) correcting element of a C_(S)/C_(C)corrector system 400 according to the present invention. Specifically,FIG. 4 shows the example C_(S)/C_(C) corrector system 400 as comprisinga magnetic multipole 402 surrounding an electrostatic quadrupole formedby a plurality of electrodes 404. FIG. 4 depicts cross sectional viewsof the electrodes 404 that illustrate that the electrodes 404 areindividually formed of an inner core 406 composed of an electricallyisolating material (e.g., a ceramic material, a vitreous material,quartz, a semiconductor material, etc.) and an outer coating 408composed of an electrically conductive material that completely enclosesthe inner core. FIG. 4 depicts an embodiment where the outer core 408does not completely enclose the inner core 406. For example, the ratioof h:g may be greater than 5 or 6 in a particular embodiment. Theelectrically conductive material is selected such that the product ofthe thickness of the outer coating (t) and the electrical conductivity(σ) of the electrically conductive material is less than 0.01Ω⁻¹, 0.001Ω⁻¹, and/or 0.0001 Ω⁻¹. In various embodiments, the outer coating 408may be electrically grounded, and/or may have a sheet resistance that isgreater than 10 kΩ, and/or greater than 100 kΩ. The presence of thisouter coating 408 on the electrodes 402 causes the amount of thermalmagnetic noise (i.e., Johnson noise) that is generated by the exampleC_(S)/C_(C) corrector system 400 to be reduced by at least 2×, 3×, or anorder of magnitude over known optical elements when a charged particlebeam 410 travels proximate to the electrodes 402.

FIG. 5 illustrates graphical relationships of the contributions ofthermal magnetic field noise (Johnson noise) to the TEM contrasttransfer function (CTF) for both an existing system using presenttechnology and a system incorporating technology from the presentdisclosure. Specifically, FIG. 5 shows a graph that illustrates thecontributions of Johnson noise to the CTF for example C_(C)/C_(S)corrector systems which comprise two quadrupole Wien filters as C_(C)correcting elements. These two elements correct for the axial chromaticaberration C_(C) of all other lenses, with a major contribution of theobjective lens. Curve 502 corresponds to the contribution of Johnsonnoise to the CTF for a first version of such an example C_(C)/C_(S)corrector system that is constructed according to prior technology.Curve 504 corresponds to the contribution of Johnson noise to the CTFfor a second version of the example C_(C)/C_(S) corrector system thatwas constructed to incorporate technology from the present disclosure.

When evaluating the contribution of thermal magnetic field noise to theTEM CTF for these two example C_(C)/C_(S) corrector systems, we considerthe common and ideal case where there are two mutually perpendicularline foci of equal length in the centers of these quadrupole Wienfilters. We further consider an axial electron (i.e., an electron whosepath starts on the optical axis in the specimen plane) with half openingangle α_(x) in the specimen plane, which has a lateral position x at thecenter of one quadrupole Wien filter (and hence x=0 in the other one).An effective focal distance f_(eff) can then be defined asf_(eff)=x/α_(x). The Johnson noise generated by the two quadrupole Wienfilters cause a Gaussian image spread in the specimen plane, with an rmsvalue σ given by:

$\begin{matrix}{{\sigma^{2} = \frac{C_{J}\mspace{11mu} C_{metal}\mspace{11mu} L\mspace{11mu} f_{eff}^{2}}{U_{r}\mspace{11mu} R^{2}}},} & (1)\end{matrix}$in which U_(r)=relativistic electron voltage=U+eU²/(2mc²), and L andR=length and inner radius of the quadrupole Wien filters. Furthermore,the constant C_(j) is defined as:

$\begin{matrix}{{C_{J} = {\frac{3}{4}\pi\eta^{2}\mu_{0}k_{B}\mspace{11mu} T}},} & (2)\end{matrix}$which is equal to 1.05×10⁻¹⁵ (in SI units) when the system is at roomtemperature; k_(B) is the Boltzmann constant. Additionally, thedimensionless constant C_(metal)≈0.085 ≡C_(non-magn) for non-magneticmetals, and it equals approximately 0.17 ≡C_(magn) for soft-magneticiron.

Curve 502 in FIG. 5 describes the contribution of thermal magnetic fieldnoise from a C_(C)/C_(S) corrector system having two C_(C) correctingelements which are magnetic multipoles with quadrupole voltages betweenV_(q) and −V_(q) on its yokes. This allows equation (2) to be evaluatedas:σ²=2C _(j) C _(magn) C _(c) γV _(q) ⁻¹  (3),in which γ=1+eU/(mc²), which expresses the image spread caused bythermal magnetic field noise in terms of the parameters of thequadrupole Wien filter. It may appear remarkable to a person skilled inthe art that the geometric parameters L and R of this element do notappear in equation 3 (as these dimensions affect the Johnson noisecontributions). However, it is noted that they are absent because theeffect of the L and R parameters on the magnification between thecorrector system and the objective lens (i.e., they affect f_(eff) whichis needed for chromatic aberration correction) causes these parametersdrop out of equation 3. In a quadrupole Wien filter according to theinvention, the magnetic multipole can have a larger radius R, leading toless Johnson noise. In terms of the parameters of this magneticmultipole, the Johnson noise rms value σ is given by:

$\begin{matrix}{{\sigma^{2} = \frac{2\mspace{11mu} C_{J}C_{magn}\mspace{11mu} C_{c}\mspace{11mu}\gamma^{2}}{\eta\mspace{11mu} U_{r}^{1/2}\mspace{11mu} R\mspace{11mu} B_{yoke}}},} & (4)\end{matrix}$in which η=√{square root over (e/(2m))}, and B_(yoke) is the maximummagnetic field at the inner radius R of the magnetic multipole. Equation4 is used to calculate curve 504. The contribution of Johnson noise tothe TEM Contrast Transfer Function (CTF) is given by:CTF(Johnson)=e ^([−2(πσk)) ² ^(])  (5),in which k is the spatial frequency.

In FIG. 5, curve 504 shows the contribution of Johnson noise to the CTFfor a C_(C)/C_(S) corrector system comprising magnetic and electrostaticquadrupoles, according to the present disclosure. Equations 4 and 5 areused to calculate curve 504, with parameters C_(C)=1.6 mm, U=300 kV, R=6mm, and B_(yoke) 0.04 Tesla. The Johnson noise produced by the innerelectrodes is assumed to be negligible.

Curve 502 shows the relationship for a first case where the electrodesof the C_(C) correcting elements do not individually comprise an innercore composed of an electrically isolating material and an outer coatingcomposed of an electrically conductive material. For practical reasons,the quadrupole voltage V_(q) is usually chosen to be smaller than 10 kV.Curve 502 is calculated for C_(C)=1.6 mm and V_(q)=6 kV, using equations3 and 5.

Examples of inventive subject matter according to the present disclosureare described in the following enumerated paragraphs.

A1. A corrector system having reduced Johnson noise generation, thecorrector system comprising: an outer magnetic multipole; an innerelectrostatic multipole, wherein a component of the inner electrostaticmultipole comprises: an inner core composed of an electrically isolatingmaterial; and an outer coating composed of an electrically conductivematerial.

A1.1. The corrector system of paragraph A1, wherein the electricallyisolating material comprises a semiconductor material.

A1.2. The corrector system of paragraph A1, wherein the electricallyisolating material comprises a ceramic material.

A2. The corrector system of paragraph A1, wherein the outer coatingcompletely encloses the inner core.

A3. The corrector system of any of paragraphs A1-A2.1, wherein thecomponent is an electrode.

A4. The corrector system of any of paragraphs A1-A3, wherein the innerelectrostatic multipole comprises a plurality of electrodes.

A4.1. The corrector system of paragraph A4, wherein each of theplurality of electrodes comprises: an inner core composed of anelectrically isolating material; and an outer coating composed of anelectrically conductive material.

A5. The corrector system of any of paragraphs A1-A4.1, wherein thecorrector is a C_(C) corrector.

A6. The corrector system of any of paragraphs A1-A4.1, wherein thecorrector is a C_(c)/C_(s) corrector.

A6.1. The corrector system of any of paragraphs A1-A4.1, wherein thecorrector is a C_(S) corrector.

A7. The corrector system of any of paragraphs A1-A6, wherein the outercoating has a sheet resistance of greater than 10 kΩ.

A7.1. The corrector system of paragraphs A7, wherein the outer coatinghas a sheet resistance of greater than 100 kΩ.

A8. The corrector system of any of paragraphs A1-A7.1, wherein theproduct of the thickness of the outer coating (t) and the electricalconductivity (σ) is less than 0.01Ω⁻¹.

A8.1. The corrector system of paragraph A8, wherein the product of thethickness of the outer coating (t) and the electrical conductivity (σ)is less than 0.001 Ω⁻¹.

A8.2. The corrector system of paragraph A8, wherein the product of thethickness of the outer coating (t) and the electrical conductivity (σ)is less than 0.0001 Ω⁻¹.

A9. The corrector system of any of paragraphs A1-A7.1, wherein the outercoating causes a reduction in Johnson noise of 2×, 3×, or an order ofmagnitude.

A9.1. The corrector system of paragraphs A9, wherein the outer coatingcauses a reduction in Johnson noise of greater than 2×, 3×, or an orderof magnitude.

A10. The corrector system of any of paragraphs A1-A9.1, wherein theouter coating is electrically grounded.

B1. An electron microscopy optical element having reduced Johnson noisegeneration, the optical element comprising: an inner core composed of anelectrically isolating material; an outer coating composed of anelectrically conductive material.

B1.1. The optical element of paragraph B1, wherein the electricallyisolating material comprises a semiconductor material.

B1.2. The optical element of paragraph B1, wherein the electricallyisolating material comprises a ceramic material.

B2. The optical element of paragraph B1, wherein the outer coatingcompletely encloses the inner core.

B3. The optical element of any of paragraphs B1-B2.1, wherein theoptical element is an electrode.

B5. The optical element of any of paragraphs B1-B4.1, wherein theoptical element is a corrector.

B5.1. The optical element of paragraph B5, wherein the optical elementis a C_(c) corrector.

B5.2. The optical element of any of paragraphs B5-B5.1, wherein theoptical element is a C_(c)/C_(s) corrector.

B5.3. The optical element of any of paragraphs B5-B5.2, wherein theoptical element further comprises at least one outer magnetic multipole.

A5.4. The corrector system of any of paragraphs B1-B5, wherein thecorrector is a C_(S) corrector.

B7. The optical element of any of paragraphs B1-B5.4, wherein the outercoating has a sheet resistance of greater than 10 kΩ.

B7.1. The optical element of paragraphs B7, wherein the outer coatinghas a sheet resistance of greater than 100 kΩ.

B8. The optical element of any of paragraphs B1-B7.1, wherein theproduct of the thickness of the outer coating (t) and the electricalconductivity (σ) is less than 0.01Ω-1.

B8.1. The optical element of paragraph B8, wherein the product of thethickness of the outer coating (t) and the electrical conductivity (σ)is less than 0.001 Ω⁻¹.

B8.2. The optical element of paragraph B8, wherein the product of thethickness of the outer coating (t) and the electrical conductivity (σ)is less than 0.0001 Ω⁻¹.

B9. The optical element of any of paragraphs B1-B7.1, wherein the outercoating causes a reduction in Johnson noise of 2×, 3×, or an order ofmagnitude.

B10. The optical element of any of paragraphs B1-B9, wherein the outercoating is electrically grounded.

C1. Use of the corrector system of any of paragraphs A1-A10.

D1. Use of the optical element of any of paragraphs B1-B10.

E1. A charged particle microscope system configured to have reducedthermal magnetic noise, the system comprising: a charged particle sourceconfigured to emit a charged particle beam towards a sample; a focusingcolumn configured to direct the charged particle beam to the sample; asample holder configured to hold the sample; a detector systemconfigured to detect emissions and/or charged particles based on thecharged particle beam interacting with the sample; and at least one ofthe corrector systems of any of paragraphs A1-A10 and/or the opticalelement of any of paragraphs B1-B10.

F1. Use of the charged particle microscope system of paragraph E1.

The systems, apparatus, and methods described herein should not beconstrued as limiting in any way. Instead, the present disclosure isdirected toward all novel and non-obvious features and aspects of thevarious disclosed embodiments, alone and in various combinations andsub-combinations with one another. The disclosed systems, methods, andapparatus are not limited to any specific aspect or feature orcombinations thereof, nor do the disclosed systems, methods, andapparatus require that any one or more specific advantages be present orproblems be solved. Any theories of operation are to facilitateexplanation, but the disclosed systems, methods, and apparatus are notlimited to such theories of operation.

Although the operations of some of the disclosed methods are describedin a particular, sequential order for convenient presentation, it shouldbe understood that this manner of description encompasses rearrangement,unless a particular ordering is required by specific language set forthbelow. For example, operations described sequentially may in some casesbe rearranged or performed concurrently. Moreover, for the sake ofsimplicity, the attached figures may not show the various ways in whichthe disclosed systems, methods, and apparatus can be used in conjunctionwith other systems, methods, and apparatus. Additionally, thedescription sometimes uses terms like “determine,” “identify,”“produce,” and “provide” to describe the disclosed methods. These termsare high-level abstractions of the actual operations that are performed.The actual operations that correspond to these terms will vary dependingon the particular implementation and are readily discernible by one ofordinary skill in the art.

What is claimed is:
 1. An electron microscopy optical element, the optical element comprising: an inner core composed of an electrically isolating material; and an outer coating composed of an electrically conductive material, wherein the product of the thickness of the outer coating (t) and the electrical conductivity (σ) is less than 0.01Ω⁻¹.
 2. The optical element of claim 1, wherein the electrically isolating material comprises a ceramic material.
 3. The optical element of claim 1, wherein the outer coating completely encloses the inner core.
 4. The optical element of claim 1, wherein the outer coating has a sheet resistance of greater than 10 kΩ.
 5. The optical element of claim 1, wherein the outer coating causes a reduction in Johnson noise of an order of magnitude.
 6. A charged particle microscope system, the system comprising: a charged particle source configured to emit a charged particle beam towards a sample; a focusing column configured to direct the charged particle beam to the sample; a sample holder configured to hold the sample′ a detector system configured to detect emissions and/or charged particles based on the charged particle beam interacting with the sample; and an electron microscopy optical element having reduced Johnson noise generation, the optical element comprising: an inner core composed of an electrically isolating material; and an outer coating composed of an electrically conductive material, wherein the outer coating has a sheet resistance of greater than 10 kΩ.
 7. The microscope system of claim 6, wherein the product of the thickness of the outer coating (t) and the electrical conductivity (σ) is less than 0.01Ω⁻¹.
 8. A corrector system, the corrector system comprising: an outer magnetic multipole; and an inner electrostatic multipole, wherein a component of the inner electrostatic multipole comprises: an inner core composed of an electrically isolating material; and an outer coating composed of an electrically conductive material, wherein the outer coating has a sheet resistance of greater than 10 kΩ.
 9. The corrector system of claim 8, wherein the electrically isolating material comprises a semiconductor material.
 10. The corrector system of claim 8, wherein the electrically isolating material comprises a ceramic material.
 11. The corrector system of claim 8, wherein the outer coating completely encloses the inner core.
 12. The corrector system of claim 8, wherein the component of the inner electrostatic multipole is an electrode, and the inner electrostatic multipole comprises a plurality of electrodes.
 13. The corrector system of claim 12, wherein each of the plurality of electrodes comprises: an inner core composed of an electrically isolating material; and an outer coating composed of an electrically conductive material.
 14. The corrector system of claim 8, wherein the product of the thickness of the outer coating (t) and the electrical conductivity (σ) is less than 0.01Ω⁻¹.
 15. A corrector system, the corrector system comprising: an outer magnetic multipole; and an inner electrostatic multipole, wherein a component of the inner electrostatic multipole comprises: an inner core composed of an electrically isolating material; and an outer coating composed of an electrically conductive material, wherein the product of the thickness of the outer coating (t) and the electrical conductivity (σ) is less than 0.01Ω⁻¹.
 16. The corrector system of claim 15, wherein the electrically isolating material comprises a semiconductor material.
 17. The corrector system of claim 15, wherein the outer coating completely encloses the inner core.
 18. The corrector system of claim 15, wherein the component of the inner electrostatic multipole is an electrode, and the inner electrostatic multipole comprises a plurality of electrodes.
 19. The corrector system of claim 18, wherein each of the plurality of electrodes comprises: an inner core composed of an electrically isolating material; and an outer coating composed of an electrically conductive material.
 20. The corrector system of claim 15, wherein the outer coating has a sheet resistance of greater than 10 kΩ. 